The present invention relates to a cross-country ski having a climbing surface fixed in a longitudinal slot, a detachable running surface, and fastening means for attaching the detachable running surface. The detachable running surface covers the length of the ski and is flush with the edges of the ski.
A wide variety of patterned ski bases are currently in use on cross-country skis. These are generically known as "no-wax" or "waxless" skis. Patterned ski bases or waxless skis are not widely used for ski mountaineering because the depth of the pattern necessary to facilitate steep climbing would overly increase gliding friction on the skier's descent.
However, detachable climbing skins are a class apart from patterned or waxless ski bases, and have been in use since the inception of skiing. Skis equipped with gripping devices such as sealskins or imitations thereof in synthetic materials applied to the soles of the skis are already known. The application of self-adhesive natural or synthetic skins has the disadvantage of imperfect adherence. Self-adhesive skins have a tendency to become soaked with water from many snow conditions which render their glue useless. Moreover, when removing the adhered skin, a part of the adhesive material may remain on the ski sole, thus preventing good sliding. In order to overcome this latter disadvantage, the sticking of strips of gripping skin in longitudinal grooves has already been suggested. This gives rise to another disadvantage, viz. the sole no longer provides a sufficiently large, smooth surface after the adhesive skin has been removed.
In an effort to eliminate these problems, inserts have recently been developed to provide a detachable climbing surface. Inserts for skis of this type normally comprise several layers, e.g., one layer comprising the means to prevent backward sliding (steps, scales, skin) on the side of the sliding surface, a supporting web, to which the above-mentioned layer is bonded and a band that is adhesive on both of its sides, one side being integrally joined to the supporting web, the other being the self-adhesive surface of the insert. As such an insert is of considerable thickness, a corresponding depth of the recess in the sliding sole of the ski is necessary. In order to achieve this, relatively thick sliding soles must be used, which in the case of cross-country skis is a disadvantage for weight reasons and/or the cost of the high-quality material for sliding soles. Otherwise, the recesses must extend into the body of the ski, thus impairing the supporting function of the lowest layer of the ski body on the one hand, and causing problems in the production on the other hand, as considerable tool wear is entailed when milling into the lowest supporting layer of the ski, which in the case of modern skis is almost exclusively made of glass-reinforced plastics. Milling also decreases the structural integrity of the ski section, resulting in a less durable ski. It is a further disadvantage that the sliding soles are conventionally produced of materials with poor adhesive qualities, e.g., polyethylene, so that the inserts are not sufficiently affixed to the recesses in such a sliding surface of polyethylene.
In addition, the fixing of permanent and undetachable gripping devices to ski soles is also known. These devices cause excessive resistance during downhill skiing and have a tendency to ice up under some conditions.
The disadvantages of the prior art are overcome by the present invention. The climbing surface is permanently attached to the ski but will not ice up. A detachable running surface is attached over the climbing surface for gliding.